Geographic Range

Yellow tangs, Zebrasoma flavescens, are reef fish found in the waters west of Hawaii and east of Japan in the Pacific Ocean. They mainly live off the coast of Hawaii, but are also found in the more western ranges of their habitat, including the islands Ryukyu, Mariana, Marshall, Marcus, and Wake. They prefer subtropical waters. (Agbayani, 2008; Waikïkï Aquarium, 1999)

Habitat

Yellow tangs are reef-associated fish. Their preferred water temperature is around 21 degrees Celsius. They inhabit coral reefs in subtropical waters, but generally do not live in tropical seas. Yellow tangs mainly live in the sub-surge zone of a coral reef, this is the area with the least wave action. Zebrasoma flavescens live at depths of 2 to 46 meters. The clear larva of yellow tangs develop into marine plankton, in this stage they are carried close to reefs where they settle in coral crevices. (Agbayani, 2008; Ogawa and Brown, 2001; Reynolds and Casterlin, 1980; Waikïkï Aquarium, 1999)

Physical Description

Yellow tangs have a clear larval stage before developing into juveniles. Juveniles and adults have a narrow, oval body. They have an average length-weight ratio between 2.93 and 3.16. They have a long snout for eating algae, a large dorsal fin with four to five spines, and an anal fin with three spines. Like other surgeonfish and tangs (Acanthuridae), yellow tangs have a white, scalpel-like spine on both sides of the tail that can be used for defense or aggression. Yellow tangs are named for their bright yellow coloring; the only area that is not yellow is the white spine. At night, this bright yellow color changes to a darker, grayer yellow with a white lateral line. (Agbayani, 2008; Froese, 1998; Guiasu and Winterbottom, 1998; Waikïkï Aquarium, 1999; Wood, 2008)

Development

Yellow tangs begin their lives as fertilized eggs floating in open water. After hatching, the clear, pelagic larvae develop in the plankton. They enter the acronurus larva stage where they develop an oval body, dorsal and ventral fins, and spines. After about ten weeks, they enter a planktonic stage. Here, waves carry them to a coral reef where they take refuge and continue to develop and grow. (Brough and Brough, 2008; Sale, et al., 1984; Waikïkï Aquarium, 1999; Wood, 2008)

Reproduction

Zebrasoma flavescens can spawn in groups or in pairs. When in groups, females release eggs and males release sperm into open water where fertilization occurs. When in pairs, the male courts a female by changing colors and exhibiting a shimmering movement. The two fish then swim upward and simultaneously release their eggs or sperm into the water. Males may spawn with multiple females in one session, while females typically spawn only once a month. (Brough and Brough, 2008; Waikïkï Aquarium, 1999; Wood, 2008)

There is no parental investment in yellow tangs beyond the fertilization of eggs.

Parental Investment

no parental involvement

pre-fertilization

provisioning

protecting

female

Lifespan/Longevity

Not much is known about the lifespan of yellow tangs. However, some sources have found them living up to about 30 years on the reef and 10 years in captivity. (Dodds, 2007; Parrish and Claisse, 2005)

Range lifespanStatus: wild

30 (high) years

Range lifespanStatus: captivity

10 (high) years

Behavior

Juvenile yellow tangs are often territorial. This trait usually diminishes as the fish mature and start to roam wider areas of the reef.
Adult tangs live singly or in small, loose groups. These groups sometimes contain other species of fish, like sailfin tang (Zebrasoma veliferum). Yellow tangs are diurnal. During the day, tangs move from place to place, grazing on algae; at night, they generally rest alone in coral reef crevices. (Agbayani, 2008; Atkins, 1981; Brough and Brough, 2008; Wood, 2008)

Home Range

When they are juveniles, yellow tangs have small home ranges that they defend, often staying within a few meters of one area. Not much is known about the home ranges of adult yellow tangs. (Parrish and Claisse, 2005)

Communication and Perception

When mating, males change colors and exhibit a shimmering movement to attract females.
In defense or aggression, yellow tangs extend their fins to full length, greatly increasing their size. They also expose their scalpel-like scales on their fins as a warning sign. They use these not only to defend themselves from predators, but also to scare away competitors for food or territory. (Brough and Brough, 2008; Waikïkï Aquarium, 1999)

Food Habits

Yellow tangs have a long, down-turned mouth with small teeth that are specialized for grazing on algae. Because they are mainly herbivores, they spend a large amount of their time grazing either alone or in groups. A large portion of their diet consists of uncalcified and filamentous algae that grows on coral reefs. In addition to smaller types of algae, yellow tangs feed on macroalgae, such as seaweed. Yellow tangs will also eat some types of zooplankton. (Guiasu and Winterbottom, 1998; Waikïkï Aquarium, 1999; Wylie and Paul, 1988)

Predation

Predators of Zebrasoma flavescens include larger fish and predatory invertebrates such as crabs and octopi. Yellow tangs rely on camouflage and their scalpel-like fins to protect themselves. To humans, these fish appear bright yellow, but, to other fish, yellow tangs blend in very well with coral reef backgrounds. According to Marshall et al. (2003) wavelength differences between yellow and average reef color become negligible at the depths where yellow tangs are found. In addition to camouflage, Zebrasoma flavescens use their scalpel-like fins for defense. (Barry and Hawryshyn, 1999; Detroit Zoological Society, 2008; Marshall, et al., 2003; Waikïkï Aquarium, 1999)

Ecosystem Roles

Yellow tangs, along with other algae feeders, are crucial parts of coral reef ecosystems. They feed on algae and seaweed that grow on the reefs, preventing them from overgrowing and killing corals. Yellow tangs are also a food source for larger fish and invertebrates. (Detroit Zoological Society, 2008; Waikïkï Aquarium, 1999)

Economic Importance for Humans: Positive

Yellow tangs are important for tourism and the aquarium trade. Their bright yellow color is well recognized by scuba divers and other tourists on Hawaiian reefs. They are also a valuable resource in aquarium trade; they are the number one collected fish for export out of Hawaii. Their coloring, hardiness, and low cost all attribute to their popularity in marine aquariums, making them one of the ten most popular fish. (Brough and Brough, 2008; Ogawa and Brown, 2001; Waikïkï Aquarium, 1999)

Economic Importance for Humans: Negative

Yellow tangs, along with other surgeonfish (Acanthuridae), are not generally dangerous. When they are young, they possess venom glands. As they age into juveniles and adults, they lose these glands. If yellow tangs are provoked, they can inflict deep injuries with the sharp blades on their tails. (Agbayani, 2008; Waikïkï Aquarium, 1999)

Glossary

body of water between the southern ocean (above 60 degrees south latitude), Australia, Asia, and the western hemisphere. This is the world's largest ocean, covering about 28% of the world's surface.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

chemical

uses smells or other chemicals to communicate

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

diurnal

active during the day, 2. lasting for one day.

ecotourism

humans benefit economically by promoting tourism that focuses on the appreciation of natural areas or animals. Ecotourism implies that there are existing programs that profit from the appreciation of natural areas or animals.

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

external fertilization

fertilization takes place outside the female's body

fertilization

union of egg and spermatozoan

herbivore

An animal that eats mainly plants or parts of plants.

heterothermic

having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

macroalgae

seaweed. Algae that are large and photosynthetic.

metamorphosis

A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.

motile

having the capacity to move from one place to another.

natatorial

specialized for swimming

native range

the area in which the animal is naturally found, the region in which it is endemic.

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

pet trade

the business of buying and selling animals for people to keep in their homes as pets.

polygynandrous

the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.

reef

structure produced by the calcium carbonate skeletons of coral polyps (Class Anthozoa). Coral reefs are found in warm, shallow oceans with low nutrient availability. They form the basis for rich communities of other invertebrates, plants, fish, and protists. The polyps live only on the reef surface. Because they depend on symbiotic photosynthetic algae, zooxanthellae, they cannot live where light does not penetrate.

saltwater or marine

mainly lives in oceans, seas, or other bodies of salt water.

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

solitary

lives alone

tactile

uses touch to communicate

territorial

defends an area within the home range, occupied by a single animals or group of animals of the same species and held through overt defense, display, or advertisement

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

venomous

an animal which has an organ capable of injecting a poisonous substance into a wound (for example, scorpions, jellyfish, and rattlesnakes).

visual

uses sight to communicate

year-round breeding

breeding takes place throughout the year

zooplankton

animal constituent of plankton; mainly small crustaceans and fish larvae. (Compare to phytoplankton.)

Disclaimer:
The Animal Diversity Web is an educational resource written largely by and for college students. ADW doesn't cover all species in the world, nor does it include all the latest scientific information about organisms we describe. Though we edit our accounts for accuracy, we cannot guarantee all information in those accounts. While ADW staff and contributors provide references to books and websites that we believe are reputable, we cannot necessarily endorse the contents of references beyond our control.

This material is based upon work supported by the
National Science Foundation
Grants DRL 0089283, DRL 0628151, DUE 0633095, DRL 0918590, and DUE 1122742. Additional support has come from the Marisla Foundation, UM College of Literature, Science, and the Arts, Museum of Zoology, and Information and Technology Services.